It was natural that the best methods of interpreting so useful a source of information should be greatly sought after, and that they should be systematised in treatises expressly devoted to the subject. One such work, the _Oneirocritica_ of Artemidôrus, is still extant. It was composed towards the end of the second century, as its author tells us, at the direct and repeated command of Apollo. According to Artemidôrus, the general belief in prophecy and in the existence of providence must stand or fall with the belief in prophetic dreams. He looked on the compilation of his work as the fulfilment of a religious mission, and his whole life was devoted to collecting the materials for it. His good faith is, we are told, beyond question, his industry is enormous, and he even exercises considerable discrimination in selecting and elucidating the phenomena which are represented to us as manifestations of a supernatural interest in human affairs. Thus his beliefs may be taken as a fair gauge of the extent to which educated opinion had at that time become infected with vulgar superstition.[351] Dreams, like oracles, were occasionally employed for the conversion of infidels. An incident of the kind is related by Aelian, a writer who flourished early in the third century, and who is remarkable, even in that age, for his bigoted orthodoxy. A certain man named Euphronius, he tells us, whose delight was to study the blasphemous nonsense of Epicurus, fell very ill of consumption, and sought in vain for help from the skill of the physicians. He was already at death’s door, when, as a last resource, his friends placed him in the temple of Asclêpius. There he dreamed that a priest came to him and said, ‘This man’s only chance of salvation is to burn the impious books of Epicurus, knead the ashes up with wax, and use the mixture as a poultice for his chest and stomach.’ On awakening, he followed the divine prescription, was restored to health, and became a model of piety for the rest of his life. The same author gives us a striking instance of prayer answered, also redounding to the credit of Asclêpius, the object of whose favour is, however, on this occasion not a human being but a fighting-cock. The scene is laid at Tanagra, where the bird in question, having had his foot hurt, and evidently acting under the influence of divine inspiration, joins a choir who are singing the praises of Asclêpius, contributing his share to the sacred concert, and, to the best of his ability, keeping time with the other performers. ‘This he did, standing on one leg and stretching out the other, as if to show its pitiable condition. So he sang to his saviour as far as the strength of his voice would permit, and prayed that he might recover the use of his limb.’ The petition is granted, whereupon our hero claps his wings and struts about ‘with outstretched neck and nodding crest like a proud warrior, thus proclaiming the power of providence over irrational animals.’[352]